1. Field of the Invention
The present invention relates to a magnetic resonance system of the type having an imaging computer, an image acquisition unit, a control arrangement including a computer, a bus, processors and memories, and having an input arrangement for the manual entry of sequence parameters.
2. Description of the Prior Art
In conventional examinations, e.g. in magnetic resonance (MR), before the measurement a control sequence, e.g. spin echo or turbo spin echo, is selected, and is modified by entering user parameters (UIPar=User Interface Parameter). In MR technology, user parameters (UIPar) of this sort can be the repetition time TR, the echo times TE or TE(i), the number of slices, the slice thicknesses, the matrix size, the image segment FOV (Field of View), the slice position, the slice rotation, the flip angle, and the saturation slices.
From the sequence and the UI parameters, data sets and/or programs are calculated that are loaded into the control hardware and are interpreted there. The control hardware basically is formed by the gradient generator, the RF generator and the data recording.
At the end of the measurement, or accompanying the measurement, the raw data are evaluated, or during the imaging magnetic resonance (MRI) images of arbitrarily rotated slices through the subject of examination are calculated. If modifications are desired, the UI parameters must subsequently be re-entered, and the sequence begins again.
The entry of the parameters has previously taken place on the display screen via an input mask in which there are provided fields for alphanumeric text or numbers, fields to be marked with a cross, or slides, on which an analog input is possible with the aid of a mouse.
Given a graphical slice positioning, the user selects a slice and moves it in parallel fashion or rotates it by setting the cursor to what are called angle points, and these are then moved.
This sort of input is inconvenient, especially if inputs are made during measurement and their effects are supposed to be observed quasi-simultaneously with the input. It is then not realistic to expect that a display screen mask and the MR images can be observed at the same time. Moreover, it is very inconvenient to place the cursor precisely on an input field, or even an angle point, using the mouse.
In U.S. Pat. No. 5,144,242, a microcoded pulse sequencer for real-time controlling of an MR system is specified in which microcommands from one memory region are loaded into another region.
U.S. Pat. No. 5,349,296 relates to an MR apparatus that is controlled by a workstation. For the reproduction of an image reconstructed from the magnetic resonance data, a scan processor is provided that controls the scan parameters and the reconstruction processor. A scan sequencer contains a master board for microcode, which controls the scan processor dependent on the commands of the scan processor. A number of codes describing the gradients and the RF pulse form is read into a memory. Dependent on a clock rate, the data are read into corresponding output registers step-by-step.
From the journal xe2x80x9cMagnetic Resonance Imaging,xe2x80x9d vol. 9 (1991), pages 627-634, an apparatus is known that can be used as an MR pulse programmer. It produces a microcode in the shortest time and transmits these data.
An object of the present invention is to provide of creating an imaging system of the type described above that enables a simple and rapid change between the various parameters, as well as a simple and rapid entry of the parameters. The above object is achieved in accordance with the principles of the present invention in a magnetic resonance system having an image computer, an image acquisition unit, a control arrangement including a control computer, a bus and processors and memories, and an imput arrangement for manually entering sequence parameters, the imput arrangement including an adjustment arrangement which allows sequence parameters to be directly modified online during an examination sequence. By means of this online MR sequence modification, the measurement sequence and the evaluation can be controlled simply and rapidly using the adjustment arrangement, e.g. in MR experiments for imaging, spectroscopy and interventional MR, since the modifications are transferred directly into the control procedure or program which is being executed.
It has proven advantageous for the input arrangement to be fashioned is in such a way that the modifications are routed directly to the control apparatus.
A rapid entry of several values is achieved if the input arrangement includes an adjustment means for the nearly simultaneous modification of at least two parameters. In this way, the measurement sequence and the evaluation can be controlled by a joystick, which supplies two or three values from a value range simultaneously or nearly simultaneously.
According to the invention, the adjustment arrangement can modify the user parameters, whereby a processor can be allocated to them for the conversion of input parameters into control parameters.
The input of the parameters can be still further simplified and accelerated if the control arrangement includes a dual buffer in which at least parts of new data are read in during a sequence that are used during a synchronous point of a sequence for controlling. A synchronous point can for example be the end of a sequence, of an individual measurement, or a manual stop command.
It has proven advantageous for a part of the control parameters to be loaded into the dual buffer in combined form in parameter blocks, which are activated at the end of the sequence.
According to the invention, the dual buffer can be a buffer memory, or its function can be implemented as software.
A particularly simple input of the parameters results if the control arrangement is formed by a joystick, a mouse or a trackball.
The user parameters can advantageously be modified by the is adjustment arrangement if they relay the entered values to a processor that converts the values into user parameters.
In a magnetic resonance system for the production of images of arbitrarily rotated slices through a subject of examination, such user parameters can, according to the invention, be for example a rotation of the slice about two axes, a displacement of the slice, a two-dimensional modification of the image segment and/or a modification of the matrix size.
According to the invention, the adjustment arrangement can also be used for image manipulation by using them to control the windowing, whereby for example the center of a window can be selected in an image brightness axis, and the amplitude window can be selected symmetrically about this center.